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Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-08-05T13:16:00Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação Armando Muchanga.pdf certa.pdf: 9213756 bytes, checksum: e7f44528d62ad3cf348371353e3934a6 (MD5) / Made available in DSpace on 2016-08-05T13:16:00Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação Armando Muchanga.pdf certa.pdf: 9213756 bytes, checksum: e7f44528d62ad3cf348371353e3934a6 (MD5) Previous issue date: 2016-02-01 / CNPq / O desenvolvimento urbano depende de vários setores, e o mais importante, além de mais caro nos custos de urbanização é o setor de infraestrutura de transporte, responsável pela pavimentação e manutenção das vias. Com o aumento acelerado de veículos que trafegam nas vias, para um departamento de transporte manter uma rede viária urbana sob os níveis de desempenho requeridos ao longo da vida útil do pavimento é necessário que haja um melhor gerenciamento das atividades de manutenção. De todos os tipos de defeitos dos pavimentos, os que mais preocupam os usuários das vias, gestor e os técnicos da manutenção são os buracos. Alinhada a este fato exposto, esta dissertação propõe um modelo Delay Time para determinar o período ótimo de inspeção e manutenção preventiva dos pavimentos asfálticos urbanos, em particular das vias da cidade de Recife, de modo a minimizar os custos de manutenção. Primeiro são exploradas as abordagem de modelo Delay Time, para analisar a que se adequa aos pavimentos asfáltico. E a abordagem proposta é Delay Time do sistema complexo, sujeito a várias falhas, com inspeção perfeita e taxa de chega de defeitos homogênea. Os pavimentos são sujeitos a vários tipos de defeitos, mas este trabalho considerou os buracos por serem os defeitos que mais gastam no custo de manutenção. Também é feita uma revisão dos trabalhos que contribuíram para investigação e aplicação do modelo Delay Time. Ainda neste trabalha é apresentado uma revisão das normas dos pavimentos asfáltico, bem como a politica de manutenção “Operação Tapa-Buraco” praticada atualmente nas vias da cidade de Recife para tapar os buracos. O modelo proposto mostra se viável e não é sensível quando variam os parâmetros de entra, os resultados obtidos são fáceis de aplicar se o setor de manutenção de pavimento da cidade de Recife incluir as hipóteses do modelo na “Operação Tapa-Buraco”. / The urban development depends on several sectors, the most important, beyond most expensive, comes from the transport infrastructure sector - that is responsible for paving and maintenance of roads. Due the rapid increase of vehicles on roads, for the transport department to keep an urban road network under the performance levels required it is necessary to invest in a better management of maintenance activities. Among all types of floors of defects, the primary concern to road users, managers and maintenance technicians are the holes. In sum to this stated fact, this dissertation proposes a Delay Time model to determine the optimal period of inspection and preventive maintenance of urban asphalt pavements, particularly for the roads of the city of Recife, in order to minimize maintenance costs. First it was explored the Delay Time model approach to analyse which applies to the asphalt pavements. The proposed approach is Delay Time of complex system, subject to several failures, with perfect inspection and a homogeneous rate of defects arrival. Besides the floors being subject to various types of defects, this work only considers holes as defects that cause more impact on the maintenance cost. It is also made a review of the works that contributed to research and application of Delay Time Models. Also in this work is presented a review of the standards of asphalt pavements, as well as the maintenance policy "Operação Tapa-Buraco", currently practiced in Recife city roads to slap the holes. The proposed model shows that it is viable and is not sensitive when varying input parameters, the results are easy to apply to the Recife city pavement maintenance industry including the model assumptions in "Operação Tapa-Buraco".

Made available in DSpace on 2014-06-12T17:39:34Z (GMT). No. of bitstreams: 2 arquivo521_1.pdf: 716833 bytes, checksum: 929cccb649732ee31f360da4b5b8aac8 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2010 / Companhia Hidro Elétrica do São Francisco / A complexidade crescente dos sistemas produtivos, aliada a necessidade cada vez maior de se reduzir os custos de produção, e aumentar a eficiência de equipamentos e sistemas, têm alavancado o desenvolvimento de modelos de otimização, não apenas para as funções de produção, mas também para as funções de apoio ao processo produtivo, como é o caso da manutenção. Alinhada a este fato, esta dissertação tem a proposta de realizar um estudo, acerca da manutenção preditiva, em componentes sujeitos a um processo de degradação. Aqui, são explicitados alguns dos principais modelos encontrados na literatura, para a modelagem deste processo, com a finalidade de se construir uma estrutura de decisão, para o estabelecimento de uma política de inspeção, com base nestes parâmetros de degradação. Partindo da constatação de que um modelo de degradação, direta ou indiretamente, relaciona esse processo físico à distribuição do tempo de vida de um determinado item, a análise realizada neste trabalho, insere, ao escopo do modelo de inspeção Delay Time, um modelo de degradação, para modelar o tempo no qual um determinado componente permanece no estado defeituoso, avaliando as conseqüências em termos dos custos da manutenção e do downtime do componente, tomando uma decisão acerca da periodicidade com que as inspeções devem ser realizadas

In this thesis, we propose a three-dimensional (3D) fold-up non-classical unipolar complementary metal-oxide semiconductor field-effect transistor (CMOS-FET) structure and its operation mechanism. We utilize a NMOS transistor having punch-through effect and a classical NMOS to realize our proposed CMOS circuit. In our proposed CMOS circuit, both driver and load transistors are based on the n-channel MOS (NMOS) structures, so, in this unipolar CMOS, the carrier used is the electron only. Hence, the delay time can be improved by 14% when compared with the conventional CMOS. Moreover, the p-channel MOS (PMOS) transistor can be eliminated in our proposed CMOS circuit. Thus, we do not need the traditional N-well technique and we also use the 3D device architecture to drastically reduce the total device area more than 69%, in comparison to a conventional CMOS. If our proposed CMOS architecture is implemented in the VLSI circuits, the packing density can be increased and the device fabrication cost can also be reduced significantly. Therefore, our proposed 3D fold-up non-classical single-carrier CMOS-FET can achieve three important requirements as follows: 1) area reduction, 2) enhanced speed, and 3) decrease cost in the system fabrication.

In this paper, we propose a novel Unipolar CMOS device in which the transport carriers are electron only. And we achieve good inverter output waveform and logic circuit applications by simulation. Duo to all n-channel (NMOS) structures are used, we call this proposed CMOS as a Unipolar CMOS. A new basic theory of utilizing the punch through effect is demonstrated to enhance the tPLH in our proposed Unipolar CMOS. The average delay time compared with the classical CMOS circuit can be improved 23% for high-performance applications. For our proposed Unipolar CMOS, all n-channel MOS are used to eliminate the N- and P-well processes and ignore the difference between the carrier mobility. In addition, the common electrodes are also exploited, hence, the layout area can be reduced to about 75%, which leads to significantly increase the packing density of CMOS circuits in the same chip.

A new shock tube targeting low temperature, high pressure, and long test times was designed and installed at the Turbomachinery Laboratory in December of 2008. The single-pulse shock tube uses either lexan diaphragms or die-scored aluminum disks of up to 4 mm in thickness. The modular design of the tube allows for optimum operation over a large range of thermodynamic conditions from 1 to 100 atm and between 600-4000 K behind the reflected shock wave. The new facility allows for ignition delay time, chemical kinetics, high-temperature spectroscopy, vaporization, atomization, and solid particulate experiments. An example series of ignition delay time experiments was made on mixtures of CH4/C2H6/O2/Ar at pressures from 1 to 30.7 atm, intermediate temperatures from 1082 to 2248 K, varying dilutions (between 75 and 98% diluent), and equivalence ratios ranging from fuel lean (0.5) to fuel rich (2.0) in this new facility. The percentage by volume variation and equivalence ratios for the mixtures studied were chosen to cover a wide parameter space not previously well studied. Results are then used to validate and improve a detailed kinetics mechanism which models the oxidation and ignition of methane and other higher order hydrocarbons, through C4, with interest in further developing reactions important to methane- and ethane-related chemistry.

Submitted by Haroudo Xavier Filho (haroudo.xavierfo@ufpe.br) on 2016-06-03T18:19:50Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DarlanMarques - Dissertação - 2015.pdf: 2076557 bytes, checksum: 43a8011bba20e4be682b2212d8ab2aab (MD5) / Made available in DSpace on 2016-06-03T18:19:50Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DarlanMarques - Dissertação - 2015.pdf: 2076557 bytes, checksum: 43a8011bba20e4be682b2212d8ab2aab (MD5) Previous issue date: 2015-10-20 / CNPq / Ter um processo produtivo íntegro que garanta a qualidade da produção e reflita em uma redução dos custos e aumento na eficácia de uma empresa, atendendo os requisitos demandados pelos stakeholders é o desejo de grande parte das organizações. Um árduo processo de gestão em relação aos elevados custos das empresas, estão intrinsecamente relacionados à manutenção, principalmente, em políticas que levem a maximização da disponibilidade do sistema e a minimização dos custos. Quando denota-se na contratação de fornecedores para realizar serviços da manutenção em uma empresa, não foge à regra, sabendo-se que cada candidato em fornecer o serviço, apresentam variações entre os seus respectivos critérios, que muitas vezes são conflitantes entre si e um modelo que dá suporte a decisão pode auxiliar o decisor a quem escolher, maximizando as suas preferências. Com este intuito, criou-se este trabalho, visto que se desenvolve um modelo de decisão multicritério utilizando a abordagem de MAUT para selecionar fornecedores de serviço em manutenção, que apresentem variações de parâmetros em meio a concepção Delay Time. Esta proposta de construção do modelo deu suporte a uma aplicação numérica na simulação de valores que chegam a utilidade individual da indisponibilidade e do custo, por fim a utilidade agregada entre ambos, que é justamente o que deseja-se saber, pois este valor da utilidade agregada permite realizar um ranking para selecionar o melhor fornecedor. Assim, criou-se três fornecedores fictícios, pela indisponibilidade de dados reais para verificar o comportamento do modelo, atribuindo-se valores ao custos (custo de falha , custo de manutenção preventiva e custo de inspeção ) e também para os tempos (tempo de realizar uma ação preventiva , tempo decorrente da uma falha e o tempo em realizar uma inspeção ). Os resultados revelaram que o primeiro fornecedor apresentou uma maior utilidade global 1((),()) de (0,89), portanto ficando na primeira colocação, seguido pelo Fornecedor 3 com 3((),()) de (0,886) e por último o Fornecedor 2 com 2((),()) de (0,856), sabendo-se que todos os três apresentam uma política que adota tempo entre inspeções (T). / Having a healthy productive process that guarantees the quality of production and reflected in a reduction in costs and increase in the effectiveness of a company, meeting the requirements demanded by stakeholders is the desire of most organizations for profit. An arduous process management in relation to the high costs of the companies are closely related to the maintenance, especially in policies that maximize system availability and minimizing costs. When is denoted in hiring vendors to perform maintenance services company, is no exception, given that each candidate to provide the service, demonstrates variations between their respective criteria, which are often conflict with each other and model that supports the decision can help the decision maker who choose to maximize your preferences. To this end, it was created this work, in that is developed a multi-criteria decision model using MAUT approach to select service providers for maintenance, which give parameter variations amid a conception Delay Time. This building proposal model has supported a numerical application in simulation values that reach individual utility of down time and cost, finally aggregate utility between them, which is precisely what you want to know, because this value utility aggregate enables a ranking to select the best supplier. Thus, it created three fictitious suppliers, the unavailability of real data to verify the model behavior, assigning values to costs (failure cost , cost of preventive maintenance and inspection cost ) and also for the times (time to perform preventive action , time resulting from a failure and the time to hold a inspection ). The results revealed that the first supplier is greater overall utility 1((),()) of (0.89), therefore being in the first place, followed by Supplier 3 with 3((),()) of (0.886) and finally with 2 Supplier 2((),()) of (0.856), it is known that all three have a policy that takes time between inspections (T).

No / Effective maintenance is a key for infrastructures’ high operational reliability. The integration of corrective repairs and schedule-based failure preventions has been a mainstream of modern maintenance, and an associated policy-making technique, delay-time modelling, is overviewed in this paper for optimising the maintenance cost-efficiency in different practical scenarios, including imperfect, opportunistic and nested maintenance. A few typical examples of its applications in minimising maintenance operating expenses are discussed in this paper and their results are explained to better demonstrate the benefits of the technique. This work aims to prepare for the future applications of the delay-time modelling in railway maintenance policy making.

In this thesis, we present a high-speed non-classical unipolar CMOS with a thick sidewall-spacer gate-oxide NMOS load. This unipolar CMOS is composed of a NMOS driver and a thick sidewall-spacer gate-oxide NMOS which replaces a PMOS as load. We focus on the investigation of punch-through current in unipolar CMOS trends. In addition, we also design a conventional CMOS for comparison. According to the simulations, the logical characteristics of our proposed CMOS are valid, in which the average propagation delay time is improved 20 % compared with the conventional CMOS. This is due to the presence of a thick sidewall-spacer gate-oxide NMOS load. For the viewpoint of device fabrication, the N well process can also be eliminated. This means that the proposed NMOS load not only improves the CMOS speed, but also reduces the fabrication cost. Thus, because of the shared-terminal output, the layout area can be significantly decreased 41 %, in comparison with the conventional CMOS.

This paper studies the integrated mobile ad-hoc networks (MANETs) and Internet network which the Mobile IP and AODV routing protocols are integrated to offer MANET nodes to set up multi-hop routes to the Internet. Gateways act as bridges for forwarding data packets between integrated MANETs and the Internet. Mobile nodes in MANETs must discover available gateways to gain access to the Internet. This study presents an adaptive gateway discovery scheme that balances efficiency and overhead by limiting the flooding scope of gateway advertisement messages. The proposed scheme dynamically adjusts the ADV_TTL according to the average delay time of network. The simulation results showed that the proposed scheme obtains the shortest average delay time while keeping the network a relatively lower overhead.